Leaf responses to soil water deficits: Comparative sensitivity of leaf expansion rate and leaf conductance in field-grown sunflower (Helianthus annuus L.)

1993 ◽  
Vol 153 (2) ◽  
pp. 189-194 ◽  
Author(s):  
V. O. Sadras ◽  
F. J. Villalobos ◽  
E. Fereres ◽  
D. W. Wolfe
Keyword(s):  
Helianthus Annuus ◽  
Soil Water ◽  
Leaf Expansion ◽  
Leaf Conductance ◽  
Expansion Rate ◽  
Water Deficits ◽  
Helianthus Annuus L ◽  
Comparative Sensitivity ◽  
Leaf Expansion Rate

Hydraulic and chemical signals in the control of leaf expansion and stomatal conductance in soybean exposed to drought stress

2003 ◽  
Vol 30 (1) ◽  
pp. 65 ◽  
Author(s):  
Fulai Liu ◽  
Christian Richardt Jensen ◽  
Mathias Neumann Andersen
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Soil Water ◽  
Leaf Growth ◽  
Chemical Signals ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Biophysical Parameters ◽  
Water Deficits ◽  
Leaf Expansion Rate

Both hydraulic and chemical signals are probably important in regulating leaf growth and stomatal conductance of soybean (Glycine max L. Merr.) under drought stress. However, until now they have not been investigated concomitantly in this species. To explore this, a pot experiment in a temperature-regulated greenhouse was conducted, in which plants were subjected to progressive drought during early reproductive stages. Biophysical parameters, viz. relative leaf expansion rate, stomatal conductance, leaf turgor, leaf [ABA], xylem pH and xylem [ABA] were followed in control and stressed plants. Drought stress decreased relative leaf expansion rate, stomatal conductance and leaf turgor, whereas it increased leaf [ABA], xylem pH and xylem [ABA]. As soil dried, significant differences between water treatments for relative leaf expansion rate, stomatal conductance, leaf turgor, leaf [ABA], xylem pH and xylem [ABA] were observed at 14, 9, 14, 14, 14 and 9 d after imposition of stress, respectively. The relationships of relative values for relative leaf expansion rate, stomatal conductance, leaf turgor, leaf [ABA] and xylem pH to the fraction of transpirable soil water (FTSW) were well described by linear-plateau functions that allowed calculation of the soil-water thresholds at which processes in stressed plants began to diverge from well-watered controls. The soil-water threshold for stomatal conductance (0.64) was significantly higher than that for relative leaf expansion rate (0.29), xylem pH (0.28), leaf [ABA] (0.27) and leaf turgor (0.25). Relative xylem [ABA] increased, first linearly (when FTSW > 0.5) and then exponentially (when FTSW < 0.5) with decreasing FTSW. Relative stomatal conductance decreased exponentially with increasing relative xylem [ABA] (r2=0.98). Decreased stomatal conductance coincided with an increase in xylem [ABA] and occurred before any significant change of leaf turgor could be detected, indicating that chemical signals (seemingly root-originated ABA) control stomatal behaviour at moderate soil water deficits. Relative relative leaf expansion rate was linearly correlated with relative leaf turgor (r2=0.93), relative xylem pH (r2=0.97) and relative leaf [ABA] (r2=0.98), implying that both hydraulic and chemical signals were probably involved in regulation of leaf expansion at severe soil water deficits.

scholarly journals Paclobutrazol Influences Salinity Responses of Peach and Olive

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 898B-898
Author(s):  
A. Abu El-Kashab ◽  
A.F. El-Sammak ◽  
A.A. Elaidy ◽  
M.l. Salama ◽  
M. Rieger
Keyword(s):  
Salt Stress ◽  
Prunus Persica ◽  
Foliar Application ◽  
Dry Weight ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Salt Tolerant ◽  
Salinity Response ◽  
Old Trees ◽  
Leaf Expansion Rate

We studied the effect of a 200-mg·liter–1 foliar application of paclobutrazol (PBZ) on growth and physiological responses of Prunus persica `Nemaguard' (salt-sensitive) and Olea europea `Manzanillo' (salt-tolerant) to salt stress. One-year-old trees were grown in 3 sand: 3 field soil: 4 pine bark media in 20-cm pots in a greenhouse and were irrigated with nutrient solutions adjusted with 0, 9, 18, or 36 mmol NaCl for peach and 0, 36, 72, 108 mmol NaCI for olive. Dry weight, photosynthesis, and leaf conductance decreased with increasing salinity for both species. However, leaf expansion rate was unaffected by NaCl. PBZ reduced dry weight for peach only, but PBZ increased photosynthesis and reduced leaf expansion rate for both species. Relative water content was decreased by salt but increased by PBZ. PBZ reduced the foliar Na and Cl content in peach but not olive. Olive had less Na in leaves than peach at 36 mmol NaCI, accumulated less C in leaves in all salt treatments, and had higher foliar Na without symptom expression. PBZ may reduce salt stress in sensitive species like peach by reducing foliar Na and Cl accumulation but has less influence on the salinity response of the more salt-tolerant olive.

scholarly journals Maximum area, expansion rate and duration of summer rape leaves

1992 ◽  
Vol 72 (1) ◽  
pp. 117-126 ◽  
Author(s):  
M. J. Morrison ◽  
D. W. Stewart ◽  
P. B. E. McVetty
Keyword(s):  
Brassica Napus ◽  
Leaf Area ◽  
Air Temperature ◽  
Ambient Air ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Regression Equations ◽  
Leaf Position ◽  
Leaf Area Duration ◽  
Leaf Expansion Rate

The vegetative development phase in summer rape (Brassica napus) is characterized by the appearance and expansion of leaves. The objectives of this research were to examine the maximum individual leaf area (LAmax), leaf expansion rate (LAX) and leaf area duration (LAD) of individual leaves as influenced by leaf position and ambient air temperature. Westar summer rape was grown from seed to maturity in controlled environment chambers set at temperatures ranging from 10 to 25 °C. Plants representing each stage of leaf development were selected at random from the population for leaf area determination. Logistic equations were used to relate the area of individual leaves to Growing Degree Days (GDD). Polynomial regression equations were used to fit curves describing the relationship between LAmax, LAX, LAD and leaf position or air temperature. As the air temperature increased the LAmax increased. LAX increased to a maximum which occurred when LAmax was at its maximum. There were no significant differences for LAX among air temperatures ranging from 13.5 to 22 °C. Mean LAX was 0.21 cm2 GDD−1. There were no significant differences in LAD due to leaf position or air temperature. Mean LAD was 140.1 GDD.Key words: Leaf area, leaf expansion rate, leaf area duration, Brassica napus

scholarly journals Leaf expansion rate and life span of floating leaves in Victoria amazonica (Poepp.) Sowerby growing in Kebun Raya, Bogor, Indonesia.

Tropics ◽  
2006 ◽  
Vol 15 (4) ◽  
pp. 429-433 ◽  
Author(s):  
Hidenobu KUNII ◽  
Senny SUNANISARI ◽  
Haruo FUKUHARA ◽  
Takuo NAKAJIMA ◽  
Fifi WIDJAJA
Keyword(s):  
Life Span ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Floating Leaves ◽  
Leaf Expansion Rate

scholarly journals Relative leaf expansion rate and other leaf-related indicators for detection of drought stress in chili pepper (Capsicum annuum L.).

2017 ◽  
Vol 11 (12) ◽  
pp. 1617-1625 ◽  
Author(s):  
Laily Ilman Widuri ◽  
◽  
Benyamin Lakitan ◽  
Mery Hasmeda ◽  
Erizal Sodikin ◽  
...  
Keyword(s):  
Drought Stress ◽  
Capsicum Annuum ◽  
Leaf Expansion ◽  
Chili Pepper ◽  
Expansion Rate ◽  
Capsicum Annuum L ◽  
Leaf Expansion Rate

Root Signals Control Leaf Expansion in Wheat Seedlings Growing in Drying Soil

1988 ◽  
Vol 15 (5) ◽  
pp. 687 ◽  
Author(s):  
JB Passioura
Keyword(s):  
Water Potential ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Wheat Seedlings ◽  
Pneumatic Pressure ◽  
Root Signals ◽  
Leaf Expansion Rate

Wheat plants were grown with their roots and soil in pressure chambers, so that the leaves could be kept highly turgid, even when the soil dried, by applying a pneumatic pressure to the roots. The relative leaf expansion rate (RLER) of plants in drying soil eventually fell behind that of well-watered plants, but, remarkably, the fall in RLER was the same whether or not the leaves were kept highly turgid. It is argued that the roots sensed the drying of the soil and sent signals to the leaves that controlled their behaviour, overriding any effects of turgor on the leaves. It is likely that the roots were sensing not only the water potential of the soil but also its hardness, which increased substantially as the soil dried.

Hydraulic conductance of intact plants of two contrasting sorghum lines, SC15 and SC1205

2013 ◽  
Vol 40 (7) ◽  
pp. 730 ◽  
Author(s):  
Sunita Choudhary ◽  
Thomas R. Sinclair ◽  
P. V. Vara Prasad
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Use ◽  
Hydraulic Conductance ◽  
Leaf Conductance ◽  
Soil Drying ◽  
Water Deficits ◽  
Intact Plants ◽  
The Impact

Low plant hydraulic conductance has been hypothesised as an approach to decrease the rate of soil water use, resulting in soil water conservation for use during late season water deficits. The impact of leaf hydraulic conductance (Kleaf) on water use characteristics was explored by comparing two sorghum (Sorghum bicolor (L.) Moench) genotypes that had been found to differ in Kleaf. Genotype SC15 had a much lower leaf conductance than genotype SC1205. Four sets of experiments were undertaken to extend the comparison to the impact of differences in Kleaf on the plant water budget. (1) Measurements of hydraulic conductance of intact plants confirmed that leaf conductance of SC15 was lower than that of SC1205. (2) The low leaf conductance of SC15 was associated with a decrease in transpiration during soil drying at a higher soil water content than that of SC1205. (3) SC15 had a restricted transpiration rate at vapour pressure deficits (VPD) above 2.1 kPa, whereas SC1205 did not. (4) Treatment with aquaporin inhibitors showed substantial differences in the sensitivity of the transpiration response between the genotypes. These results demonstrated that low Kleaf in SC15 was associated with conservative water use by restricting transpiration at higher soil water content during soil drying and under high VPD. Tests with inhibitors indicate that these differences may be linked to differences between their aquaporin populations. The differences between the two genotypes indicated that the traits exhibited by SC15 would be desirable in environments where soil water deficits develop.

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